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A word about digital power

A word about digital power

You may well have come across the expression ‘digital power’ in recent months, and you may be wondering whether it might have something to contribute to your industrial power supply. The answer is probably ‘not yet’, but in the meantime let’s just clarify what it is and what it does.

There are two categories of digital power: digital control and digital power management. We’ll start with digital control. This is something that would be used internally within a power device.

Most switched-mode AC-DC and DC-DC power supplies or converters regulate or control via analogue techniques rather than digital, although use of pulse width modulation in switching regulator circuits can be a little like digital control. More recently, we have seen the development of integrated circuits which are at least partly digital in their nature for control of voltage, power factor correction, pulse width modulation and various other factors.

These integrated circuits can be programmed by engineers with the necessary knowledge of digital and analogue electronics, of which the universities are now producing large numbers. Their big disadvantage is cost, although in time the costs may fall sufficiently to compete with analogue circuits. Another, potentially, is the fact that their operation requires a high-speed clock, which might add to the radiated and conducted ‘noise’ of the system. In their favour is the possibility that they might ultimately deliver advantages in terms of fault diagnostics, fault prevention and increased power efficiency.

Digital power management is about providing external communication and control between a master controller and the power device. Digital links between primarily analogue power systems and external computers or controllers already exist, as in RS232, RS485, GPIB and 12C bus for instance.

For the new digitally controlled power devices, a number of digital power management control and communication technologies have been developed. Power Management Bus and Z-One are examples. Unfortunately, at the moment they tend to be incompatible and non-interchangeable, which is another good reason for delaying any decision on using digital power until things have settled down somewhat.

As digital control and digital power management continue to develop, they will certainly offer advantages. The question you must ask, at any stage in that development, is whether the advantages justify the cost of moving away from the proven analogue technology that we currently enjoy.